tournaments.js

const app = Application.currentApplication()
app.includeStandardAdditions = true
let Calendar = Application("Calendar")

const rounds = [
    ["Round 1",	"12/26/2022 17:00"],
    ["Round 2",	"12/27/2022 10:00"],
    ["Round 3",	"12/27/2022 17:00"],
    ["Round 4",	"12/28/2022 10:00"],
    ["Round 5",	"12/28/2022 17:00"],
    ["Round 6",	"12/29/2022 10:00"],
    ["Round 7",	"12/29/2022 17:00"],
    ["Round 8",	"12/30/2022 09:30"],
    ["Round 9",	"12/30/2022 16:30"]
]

const [cal] = Calendar.calendars.whose({name: "Home"})

for (const [summary, dateStr] of rounds) {
    const startDate = new Date(dateStr)
    const aux = new Date(dateStr)
    const endDate = new Date(aux.setHours(aux.getHours() + 3))
    const event = Calendar.Event({ summary, startDate, endDate })
    cal.events.push(event)
}